blood claws and grey hunters. Blood claws are essentially new initiates who are thrown into the ranks to get killed. Grey hunters are more trained and can carry a boltgun chainsword and bolter all at the same time. ^^ plus 1+ attack. While blood claws cannot wield boltguns.

Give chaos all the marine stuff, and you become nothing more than a stylized chapter. As it is, you're still too similar for my liking. As far as I care, if it has power armour on standard troops, it's faggish. Including GKs, but your standard troops there actually cost nearly as much as a DE HQ choice.